Optical body, window member, fitting, solar shading device, and building

Abstract

An optical body includes a first optical layer having a concave-convex surface, a wavelength selective reflecting layer formed on the concave-convex surface, and a second optical layer formed on the wavelength selective reflecting layer and embedding the concave-convex surface. The wavelength selective reflecting layer selectively directionally reflects light in a particular wavelength band while transmitting light other than the particular wavelength band therethrough. The concave-convex surface is made up of a plurality of triangular pillars arrayed in a one-dimensional pattern, and the triangular pillar has an apex angle α and a slope angle β, the apex angle α and the slope angle βsatisfying a predetermined relationship.

Description

TECHNICAL FIELD[0001]The present invention relates to an optical body, a window member, a fitting, a solar shading device, and a building. More particularly, the present invention relates to an optical body for directionally reflecting incident light.BACKGROUND ART[0002]Recently, cases of coating a layer, which partly absorbs or reflects the sunlight, on architectural glasses for high-rise buildings and housings, vehicular window glasses, etc. have increased. Such a trend represents one of energy-saving measures with the view of preventing global warming, and it is intended to reduce a load of cooling equipment, which is increased with optical energy incoming from the sun, entering the indoor through windows, and raising the indoor temperature. The optical energy incoming with the sunlight is primarily provided in a visible range at wavelengths of 380 to 780 nm and in a near infrared range at wavelengths of 780 to 2100 nm. Because transmittance of light in the latter near infrared r...

AI Technical Summary

Benefits of technology

[0008]The above-described optical body can retro-reflectively reflect the incident light by reflecting the incident light three times with the wavelength selective reflecting layer. However, because the number of times of reflections is large, the wavelength selective reflecting layer absorbs light in amount about three times that absorbed by a flat plate and an amount of generated heat increases. Accordingly, when the above-described optical body is used as a film for a window, people feel hot with air in a space near the window and an air conditioner is operated at a higher utilization rate, whereby an amount of CO2 omission is increased.

[0025]In the optical body of the present invention, the concave-convex surface is formed by arraying asymmetrical triangular pillars in a one-dimensional pattern, and the wavelength selective reflecting layer is formed on the concave-convex surface. Accordingly, when the optical body of the present invention is applied to an adherend such as a window member, it can reflect the light in the particular wavelength band upward while transmitting light other than the particular wavelength band therethrough. Also, when the optical body of the present invention is applied to, e.g., a window member of a building, it can directionally reflect the light in the particular wavelength band to be kept from entering a predetermined space inside the building, for example, while allowing the light other than the particular wavelength band to be taken into the predetermined space.

[0027]According to the present invention, as described above, in the optical body capable of reflecting the light in the particular wavelength band while transmitting the light other than the particular wavelength band therethrough, an improvement in safety and energy saving can be realized by reducing heat generation attributable to absorption of the light. Further, a high upward reflectance can be obtained.

Problems solved by technology

However, those reflecting layers are formed on a flat window glass, and they can just specularly reflect the incident sunlight.

Such a local temperature rise causes the problems that, in urban areas, a heat island phenomenon is accelerated, and that the lawn grass does not grow only in areas irradiated with the reflected light.

This raises the problems that the shield ability of the pigment layer is insufficient, and that the glass may be cracked due to thermal stress.

Further, there is another problem that the pigment layer is poor in weatherbility and is less convenient when used in high-rise buildings in which frequent replacement of the pigment layer is difficult.

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